<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
            div{
                text-align:center;
                width:200px;
                height:200px;
                background-color:red;
                margin-left: auto;
                margin-right: auto;
            }
        
        
        </style>
</head>
<body>
    <div>hello world</div>
</body>
</html>